RF U.S. Pat. No. 2,137,126 describes a method for investigating of biological liquids, which involves IR-spectrum analyser assisted study of the liquid previously diluted with a water-alcohol mixture in a 1:1 proportion. The major drawback of this method is that it causes deterioration of the native structure of the biological liquid, which carries essential information on its nature.
There is a description of the effect of dehydration self-organization of biological liquids (V. N. Shabalin, S. N. Shatokhina, Autogeneous rhythms and self-organization of biological liquids//BEBM, 1996, vol. 122, No. 10, p. 364-371). This effect consists in a characteristic redistribution of the components in a drop of a multi-component biological liquid as it is drying up, which causes the resulting dry film to have a distinct zone structure and a certain super-molecular formations reflecting the peculiarity of its liquid-crystalline structure governed by chemical composition.
This principle underlies, for example, the method for assessing the homeostasis state of a living organism, as described in RF U.S. Pat. No. 2,007,716. Essentially, it is a morphological study on a dried-up drop of biological liquid in polarized light and assessment of the normal and pathological structures formed thereby.
The same principle is used in the method for assessing the homeostasis state of a living organism according to RF U.S. Pat. No. 2,127,430. In this method a liquid biological medium, for example, blood plasma or serum, urine, tear drop, etc., dries up under the impact of some external or internal factors, and when the water has evaporated, the resulting crystallogram is examined in nonpolarized light. If the structural elements are clustered and complex morphological formations take place, development of a pathological process and disturbance of the homeostasis are presented; in contrast, well-ordered and oriented elements in the absence of large complex aggregations indicate improvement of the physical condition, hence, the homeostasis is judged as compensated.
The shortcoming of this technique, just as of the above method described in RF U.S. Pat. No. 2,007,716, is a long time the specimen take to dry up (24 to 48 hours) and, therefore, a long duration of the research. It also takes specially trained personnel to do proper diagnostics of morphological structures.
U.S. Pat. No. 5,798,452 describes a method for liquids analysis, which involves immersing a piezoelectric resonator in the liquid in question, this resonator being an element of an ultrasonic generator and coming in the form of a thin plate providing for excitation in it of thickness shear modes. The piezoelectric plate is designed to ensure confinement of a thin film of the liquid within the assigned area on its surface. The shear modes excited in the piezoelectric plate induce similar oscillations in the confined layer of the test liquid. This causes a shift of frequency of the ultrasonic generator through the electrical impedance arising thereof which, in turn, is determined by the mechanical impedance of the test liquid layer being confined on the surface of the piezoelectric plate. By measuring the frequency shift of said ultrasonic generator one can find the mechanical impedance of said confined layer of the liquid, which provides data on the viscosity and density of said liquid. In accordance with the invention described in the same patent, apparatus is provided for liquid analysis using this method. The apparatus includes an ultrasonic frequency oscillator incorporating a piezoelectric resonator, frequency meter and recorder. The test liquid comes in direct contact with the resonator surface.
The method and apparatus for investigating a liquid as described in U.S. Pat. No. 5,798,452 enable one to determine viscosity and density of the test liquid at a specified point in time. However, this parameter does not provide sufficient information on the composition of a liquid if it is multi-component.